Olefins, especially linear olefins, serve as feedstocks for the chemical industry. They can be converted to corresponding alcohols or aldehydes. Higher molecular weight alcohols can further be ethoxylated with ethylene oxide or propylene oxide in the presence of a catalyst to form conventional detergents while lower molecular weight alcohols can be esterified with aromatic acids to form plasticizers. Alpha olefins are used as comonomers for high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), intermediates for synthetic lube oils and lubel oil additives, paper sizings and other specialty chemicals. An economically viable process for producing linear olefins in substantial quantities by cracking and dehydrogenating paraffinic feedstock, especially when combined with a subsequent ethenolysis process to produce alpha olefins with three to thirty carbon atoms, preferably six to twenty carbon atoms, is therefore of substantial commercial interest.
U.S. Pat. No. 3,592,867, patented July 13, 1971, discloses a two-step process for producing ethylene which involves, in a first step, dehydrogenating propane to propylene using a non-acidic, Group VIII noble metal catalyst; and in a subsequent second step, cracking of the resulted propylene with a Group VIII metal component hydrocracking catalyst containing nickel or rhodium.
U.S. Pat. No. 3,725,495, issued Apr. 3, 1973, discloses a process for catalytic cracking, in the presence of steam, of paraffins to produce olefins over a catalyst containing 50-80 wt. % of zirconium and/or hafnium, 5-40 wt. % of oxide of chromium, manganese and/or iron, and 0.1-10 wt % of a compound of an alkali metal and or an alkaline earth metal. When naphtha was cracked by this process, ethylene, propylene and butylenes are produced.
European patent application 219,272, published Apr. 22, 1987, disclosed a process for ethylene production from propane over a ZSM-23 zeolitic catalyst.
European patent application 219,271, published Apr. 22, 1987, disclosed a process for ethylene production from propane over a ZSM-5 zeolitic catalyst.
All of these processes require the use in the first catalytic cracking step of either transition metals or zeolites as catalysts which are relatively expensive. The expense for catalyst is one of the major costs in a catalytic cracking process. Moreover, the use of conventional zeolites as catalysts for the cracking of paraffinic feedstocks quite often produce a variety of products: olefins, both branched and straight chain, aromatics, paraffins and other products resulting from dealkylation, aromatic side-chain scission, isomerization, condensation and disproportionation reactions. Furthermore, none of these processes disclose a method for making alpha olefins with primarily more than 5 carbon atoms. An economically viable process which would crack and dehydrogenate paraffinic feedstock in a single step using a less costly catalyst that would produce only linear olefins, preferably linear olefins with primarily C.sub.6 to C.sub.30, in substantial quantities and which product can be converted conveniently into alpha olefins, would be of commercial significance, since the linear alpha olefins can be used as feedstocks to produce higher valued end products.